CN107162457A - A kind of method of delayed ettringite formation in limitation concrete - Google Patents
A kind of method of delayed ettringite formation in limitation concrete Download PDFInfo
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- CN107162457A CN107162457A CN201710394236.1A CN201710394236A CN107162457A CN 107162457 A CN107162457 A CN 107162457A CN 201710394236 A CN201710394236 A CN 201710394236A CN 107162457 A CN107162457 A CN 107162457A
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- barium salt
- coating
- polyvinyl alcohol
- salt powder
- barium
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B20/00—Use of materials as fillers for mortars, concrete or artificial stone according to more than one of groups C04B14/00 - C04B18/00 and characterised by shape or grain distribution; Treatment of materials according to more than one of the groups C04B14/00 - C04B18/00 specially adapted to enhance their filling properties in mortars, concrete or artificial stone; Expanding or defibrillating materials
- C04B20/10—Coating or impregnating
- C04B20/1018—Coating or impregnating with organic materials
- C04B20/1029—Macromolecular compounds
- C04B20/1033—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
Abstract
The present invention relates to a kind of method of limited delay entringite generation, and in particular to a kind of with coating method of the high polymer material to barium salt, adds in the concrete barium salt particle of polyvinyl alcohol coating when being technically characterized in that concrete mixing, is then well mixed.The method of the present invention can adjust and control its content after delayed ettringite formation, while the present invention has also expanded the use scope of high sulfur content admixture such as fluidized bed combustion coal ash/slag, and the final goods form of the present invention is powder, is easy to store and transports.
Description
Technical field
The present invention relates to a kind of method of limited delay entringite generation, and in particular to one kind high polymer material is to barium salt
Coating method.
Background technology
In mass concrete, 2 ~ 3 days internal temperature rises may be up to nearly 100 °C, and entringite decomposition temperature is 70 °C,
But temperature is when dropping to less than 70 °C, entringite can be generated again, i.e. delayed ettringite.Concrete meeting after delayed ettringite formation
Cracking is expanded, not only intensity is seriously reduced, and corrosive medium can be easier to penetrate into inside concrete, so as to influence to mix
Solidifying soil durability.Delayed ettringite formation in cement concrete is the major reason for causing destroying concrete structure, therefore is limited
Delayed ettringite formation processed is necessary.Current major control measure has：
（1）When delayed ettringite and alkali occur jointly, serious swelling cracking can occur for concrete, therefore can take one
Setting down measures prevents the generation of alkali, so as to reduce the harm that delayed ettringite is brought.Meeting associated specifications
In the case of mass concrete particular/special requirement, as far as possible using low hydration heat cement, while strictly controlling alkaline content of cement.Choosing
Preferentially matter aggregate, without using the aggregate for being likely to occur alkali.Used additive and admixture all should be controlled strictly
Harmful substance processed.
（2）When meeting concrete strength performance, workability and durability etc. and requiring, cement is reduced as far as possible and is used
Amount, admixture such as slag powders, flyash replace part of cement, and control water-cement ratio, select reasonable grading of aggregates and sand coarse aggregate ratio, and make
With high performance additive, folk prescription concrete water amount is reduced.
In summary, be to the control method of delayed ettringite formation at present it is preventative, and concrete preparing and
In work progress, influence factor is more complicated, once a certain link is not controlled still delayed ettringite formation unavoidably.
The present invention carrys out the generation of limited delay entringite in line with effective, practical, prevention, industrialized target, so as to realize
Improve concrete durability, extend the target of concrete life.
The content of the invention
For the deficiency of existing delayed ettringite formation method for limiting, with precautionary measures complexity, validity is uncontrollable especially
The problem of, the present invention proposes a kind of method of limited delay entringite generation, so as to realize that raising concrete durability, extension are mixed
The goal of the invention in solidifying soil life-span.
A kind of method of delayed ettringite formation in limitation concrete, when step is concrete mixing, according to weight ratio,
The barium salt particle of polyvinyl alcohol coating is added into the concrete according to 1 ~ 5% ratio of gel rubber material weight in the concrete
In, then it is well mixed.
Preparation method for the barium salt particle for the polyvinyl alcohol coating for realizing above-mentioned technical proposal goal of the invention is as described below.
A kind of preparation method of the barium salt particle of polyvinyl alcohol coating, comprises the following steps,
1) under heating condition, polyvinyl alcohol water solution is prepared, stirs and is made into coating solution；
2) barium salt powder is added in bottom spraying type or rotary drum fluid bed, then the barium salt powder granule surface preheated；
3) two-fluid shower nozzle or jet head sets are used by step 1）The coating solution prepared sprays to step 2）Barium salt powder after preheating
Body so that the coating solution forms thin film on the barium salt powder granule surface；
4) heated-air drying is blown into by the barium salt powder of coating, is subsequently cooled to room temperature；
5) by step 4）What is prepared is sieved by the barium salt powder of coating, that is, obtains the barium salt particle of polyvinyl alcohol coating
Finished product；
6) packaging and storage；
Wherein,
In step 1）In, heating-up temperature is 50 ~ 100 °C, and the degree of polymerization of the polyvinyl alcohol is 1400 ~ 2500, alcoholysis degree
For 70 ~ 99%, the concentration of the polyvinyl alcohol water solution is 3 ~ 15%；
In step 2）In, the barium salt powder is barium salt powder readily soluble under normal temperature, 2 ~ 10 microns of grain graininess, preheating temperature
For 40 ~ 80 °C；
In step 3）In, the pressure of shower nozzle atomization is 0.10 ~ 0.50Pa, 0.3 ~ 0.8Pa of compressed air pressure, the coating
Flow quantity is 500 ~ 1400mL/h, according to weight ratio, and the coating solution consumption is the 5 ~ 20% of the barium salt powder weight；
In step 4）In, the hot blast temperature being blown into is 40 ~ 80 °C；
In step 5）In, the fineness sieved by the barium salt powder of coating is 30 ~ 80 microns.
To achieve the above object of the invention, barium salt powder readily soluble preferably under normal temperature is barium hydroxide, barium nitrate, barium chloride.
A kind of barium salt particle of polyvinyl alcohol coating prepared by foregoing invention method, adds concrete and is well mixed, according to
Weight ratio, institute is added according to 1 ~ 5% ratio of gel rubber material weight in the concrete by the barium salt particle of polyvinyl alcohol coating
State in concrete and be well mixed, the generation for limiting delayed ettringite in concrete.
The present invention technical principle be：The crystal structure formula of entringite is Ca6[Al(OH)6·12H2O]2·(SO4)3·
(H2O)2.We have synthesized pure ettringite, and discovery entringite soaks in 0.5% barium salt solution will be complete after 0.5 h
Disappear, XRD spectrum is primarily present the diffraction maximum of barium sulfate, illustrates that entringite is highly susceptible to the attack of barium ions and decomposed, its
The sulfate radical contained in structure is converted into barium sulfate.
Although barium ions can effectively decompose entringite, it can not be added when concrete is just stirred, because it can cause two
Water gypsum（Dihydrate gypsum typically is used as adjustable solidification agent in portland cement）Failure.Dihydrate gypsum can react life with barium ions
Into barium sulfate, such entringite would not be generated initial stage in hydrated cementitious, then the first of concrete, final setting time will be by shadows
Ring.Accordingly, it would be desirable to use slow release method to barium ions.
Searching is a kind of can be in 70 °C or so hydrolysis or the aqueous high molecular materials dissolved, by its coating in barium salt particle table
Face, it is possible to achieve the effect of barium ions sustained release.But key is to find suitable macromolecule coated fertilizer, especially its dissolution characteristics
Or hydrolysis properties are consistent with cement hydration process.
The present invention wraps up a floor height molecular film outside barium salt powder, it is dissolved or is hydrolyzed at the appropriate time, so that
Discharge the growing amount that barium ions regulates and controls entringite.
The innovation of the present invention does not simultaneously lie in the technical principle of the above, and innovation of the invention is according to principles above, pin
A kind of method of controllable delay entringite generation is proposed to mass concrete, the present invention can effectively decompose calcium alum using barium ions
The characteristic of stone is release-controlled coated to barium ions, make its discharged at 70 °C or so with entringite react so that reach effectively regulation and
Control the generation of delayed ettringite in mass concrete.
Beneficial effects of the present invention：
1. the method for existing control entringite generation is all to put prevention first, and can not be eliminated or regulated and controled after its generation,
And the method for the present invention adjusts and controlled its content after delayed ettringite formation.
2. this patent can also expand the use scope of high sulfur content admixture such as fluidized bed combustion coal ash/slag, because the appropriate moment releases
Barium ions can consume unnecessary sulfate ion, therefore fluidized bed combustion coal ash/slag incorporation in concrete can be increased.Solid sulfur ash
Anhydrous gypsum content is far above ordinary fly ash in slag, and volume stability is likely to result in when being used as concrete admixture not
It is good, therefore volume of the fluidized bed combustion coal ash/slag in concrete be very limited.And after barium salt powder is added, anhydrous gypsum can be converted
For barium sulfate, so as to eliminate the hidden danger that anhydrous gypsum too high levels are brought.
3. final goods form is powder, facilitate simple and direct when storing, transport and using.
Brief description of the drawings
Fig. 1 is that entringite reacts product X RD collection of illustrative plates after 0.5 h with various concentrations barium salt.
Fig. 2 is H-3250D comparators.
Embodiment
With reference to specific embodiment, the invention will be further described.
With the readily soluble barium salt powder of polyvinyl alcohol coating.
Readily soluble barium salt powder is barium hydroxide in embodiment.
Experiment uses H-3250D comparators（HUMBOLDT companies of the U.S.）Test specimen expansion rate is tested, than long rod full-length
For 295mm.
Embodiment 1
1）Under 50 °C, compound concentration is 5% polyvinyl alcohol water solution, and the polyvinyl alcohol degree of polymerization used is 1700, and alcoholysis degree is
88%, then stir and be made into coating solution；
2）It is that the readily soluble barium salt powder of 3 microns is added in bottom spraying type or rotary drum fluid bed by granularity, makes the powder granule table
Face is preheated to 50 °C；
3）Polyvinyl alcohol water solution is sprayed to the barium salt powder after preheating using two-fluid shower nozzle or jet head sets, polyvinyl alcohol is water-soluble
Liquid forms one layer of coating on barium salt powder granule surface, the Pa of sprinkler pressure 0.20 in spray process, compressed air pressure 0.4Pa,
Polyvinyl alcohol water solution flow 600mL/h, polyvinyl alcohol layer consumption are the 6% of barium salt powder weight；
4）The heated-air drying for being blown into 50 °C is subsequently cooled to room temperature by the barium salt powder of coating；
5）By being sieved by the barium salt particle of polyvinyl alcohol coating for above-mentioned acquisition, screening fineness is controlled below 50 microns,
It can obtain powdery finished product；
6）Packaging and storage.
7）Using the net slurry gelling system of portland cement-fluidized bed combustion coal ash/slag, i.e., according to weight ratio, portland cement and solid sulphur
The ratio of lime-ash is（70：30）.Portland cement and fluidized bed combustion coal ash/slag SO3Content is respectively 2.47% and 8.83%, net slurry gelling system
SO in system3Content is 4.38%.SO in portland cement and fluidized bed combustion coal ash/slag3Mainly exist in anhydrous gypsum form.National regulations,
SO in Portland cement3Content must not exceed 3.5%, and coating barium salt powder volume is can destroy this part more than 3.5%
SO3I.e. 0.88% is foundation.Coating barium salt powder volume is added according to the 1.88% of gel material content.Using 25*25*280mm
Three gang moulds are molded, and take consumptive use of water normal consistence, form removal after 1 day, test block are carried out steam-cured, and temperature is 75 °C, continues 0.5 hour.
Subsequent test block, which is soaked in water, to be conserved, and the linear expansion rate for adding test specimen after coating barium salt powder is determined after 28 days, and with not adding
The test specimen of the powder is contrasted, it is found that expansion rate declines 49.6%.
Swell value calculation formula：e=(Kn-K0)/L0, wherein e is linear expansion rate, unit mm/m； K0Initially compare for test specimen
Long instrument reading, unit mm；KnFor test specimen comparator reading, unit mm after 28 d；L0For the initial length of test specimen, unit m.Through meter
Calculate, the test specimen expansion rate for being not added with coating barium hydroxide is (0.574-0.352)/(0.295+0.000352)=0.752 mm/
M, the test specimen expansion rate added after coating barium hydroxide is (0.654-0.542)/(0.295+0.000542)=0.379 mm/
M, by contrast expansion rate reduction about (0.752-0.379)/0.752 × 100%=49.6%.
Embodiment 2
1）Under 80 °C, compound concentration is 6% polyvinyl alcohol water solution, and the polyvinyl alcohol degree of polymerization used is 1700, and alcoholysis degree is
92%, then stir and be made into coating solution；
2）It is that the readily soluble barium salt powder of 5 microns is added in bottom spraying type or rotary drum fluid bed by granularity, makes the powder granule table
Face is preheated to 70 °C；
3）Polyvinyl alcohol water solution is sprayed to the barium salt powder after preheating using two-fluid shower nozzle or jet head sets, polyvinyl alcohol is water-soluble
Liquid forms thin film on barium salt powder granule surface, the Pa of sprinkler pressure 0.40 in spray process, compressed air pressure 0.6Pa,
Polyvinyl alcohol water solution flow 1000mL/h, polyvinyl alcohol layer consumption are the 10% of barium salt powder weight；
4）70 °C of heated-air dryings are blown into by the barium salt powder of coating, room temperature is subsequently cooled to；
5）By being sieved by the barium salt particle of polyvinyl alcohol coating for above-mentioned acquisition, screening fineness is controlled below 100 microns,
It can obtain powdery finished product；
6）Packaging and storage.
7）Using portland cement-fluidized bed combustion coal ash/slag（According to weight ratio, portland cement/fluidized bed combustion coal ash/slag=70：30）It is net
Starch gelling system.Portland cement and fluidized bed combustion coal ash/slag SO3Content is respectively SO in 2.47% and 11.61%, net slurry gelling system3Contain
Measure as 5.21%.SO in portland cement and fluidized bed combustion coal ash/slag3Mainly exist in anhydrous gypsum form.National regulations, common silicic acid
SO in salt cement3Content must not exceed 3.5%, and coating barium salt powder volume is can destroy this part SO more than 3.5%3I.e. 1.71%
For foundation.Coating barium salt powder volume is added according to the 3.66% of gel material content.It is molded using the gang moulds of 25*25*280mm tri-,
Take consumptive use of water normal consistence, form removal after 1 day carries out test block steam-cured, and temperature is 85 °C, continues 0.5 hour.Subsequent test block immersion
Yu Shuizhong is conserved, and the linear expansion rate for adding test specimen after coating barium salt powder is determined after 28 days, and with not adding the test specimen of the powder
Contrasted, it is found that expansion rate declines 66.4%.
It is computed, the test specimen swell value for being not added with coating barium hydroxide is about (0.716-0.466)/(0.295+
0.000466)=0.846 mm/m, and add test specimen swell value after coating barium hydroxide be about (0.792-0.708)/
The mm/m of (0.295+0.000708)=0.284, by contrast expansion rate reduction about (0.846-0.284)/0.846 ×
100% = 66.4%。
Claims (5)
1. a kind of method for limiting delayed ettringite formation in concrete, it is characterised in that when concrete is mixed, according to weight ratio,
The barium salt particle of polyvinyl alcohol coating is added into the coagulation according to 1 ~ 5% ratio of binder materials weight in the concrete
In soil, then it is well mixed.
2. the preparation method of the barium salt particle of polyvinyl alcohol coating described in claim 1, it is characterised in that comprise the following steps,
（1）Under heating condition, polyvinyl alcohol water solution is prepared, stirs and is made into coating solution；
（2）Barium salt powder is added in bottom spraying type or rotary drum fluid bed, then the barium salt powder granule surface preheated；
（3）Using two-fluid shower nozzle or jet head sets by step 1）The coating solution prepared sprays to step 2）Barium salt powder after preheating
Body so that the coating solution forms thin film on the barium salt powder granule surface；
（4）Heated-air drying is blown into by the barium salt powder of coating, room temperature is subsequently cooled to；
（5）By step 4）What is prepared is sieved by the barium salt powder of coating, that is, obtains the barium salt of polyvinyl alcohol coating
Grain finished product；
（6）Packaging and storage；
Wherein,
In step（1）In, heating-up temperature is 50 ~ 100 °C, and the degree of polymerization of the polyvinyl alcohol is 1400 ~ 2500, alcoholysis degree
For 70 ~ 99%, the concentration of the polyvinyl alcohol water solution is 3 ~ 15%；
In step（2）In, the barium salt powder is barium salt powder readily soluble under normal temperature, 2 ~ 10 microns of grain graininess, preheating temperature
Spend for 40 ~ 80 °C；
In step（3）In, the pressure of shower nozzle atomization is 0.10 ~ 0.50Pa, 0.3 ~ 0.8Pa of compressed air pressure, the bag
Clothing flow quantity is 500 ~ 1400mL/h, according to weight ratio, the coating solution consumption for the barium salt powder weight 5 ~
20%；
In step（4）In, the hot blast temperature being blown into is 40 ~ 80 °C；
In step（5）In, the fineness sieved by the barium salt powder of coating is 30 ~ 80 microns.
3. preparation method according to claim 2, it is characterised in that readily soluble barium salt powder is hydroxide under the normal temperature
Barium or barium nitrate.
4. a kind of barium salt particle of polyvinyl alcohol coating prepared by preparation method described in claim 2.
5. a kind of purposes of the barium salt particle of polyvinyl alcohol coating described in claim 4, it is characterised in that prolong in limitation concrete
The purposes of the generation of slow entringite.
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| CN201710394236.1A CN107162457B (en) | 2017-05-28 | 2017-05-28 | A kind of method of delayed ettringite formation in limitation concrete |
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| CN201710394236.1A CN107162457B (en) | 2017-05-28 | 2017-05-28 | A kind of method of delayed ettringite formation in limitation concrete |
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| CN107162457B CN107162457B (en) | 2019-07-09 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111925157A (en) * | 2020-07-08 | 2020-11-13 | 中国电力科学研究院有限公司 | Chloride ion curing method for concrete |
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2017
- 2017-05-28 CN CN201710394236.1A patent/CN107162457B/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111925157A (en) * | 2020-07-08 | 2020-11-13 | 中国电力科学研究院有限公司 | Chloride ion curing method for concrete |
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